Abstract: To improve beam quality and focusability performance, an adaptive optical system, which is based on the phase-conjugated principle and consists of Hartmann-Shack sensor, deformable mirror, control unit and software, was installed in the SILEX-I laser facility to correct its wavefront aberrations. The wavefront data and far-field focal spots were measured and analyzed. The results show that, the peak-valley value of the wavefront decreases from 1.885 μm to 0.438 μm and the root mean square value reduces from 0.379 μm to 0.052 μm with this adaptive optical system. In addition, the far-field focal spot is improved and the energy in the region where the intensity of each point is greater than 1/e2 of the laser beam peak intensity is 72.4% of the total energy after the wavefront aberrations